Katy Perry and Allison Williams attend the Unicef SnowFlake Ball at Cipriani 42nd Street on November 27, 2012 in New York City. (Photo by Stephen Lovekin/Getty Images)

Katy Perry and Allison Williams attend the Unicef SnowFlake Ball at Cipriani 42nd Street on November 27, 2012 in New York City. (Photo by Stephen Lovekin/Getty Images)

Photo: Getty Images

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Katy Perry and Harry Belafonte attend the Unicef SnowFlake Ball at Cipriani 42nd Street on November 27, 2012 in New York City. (Photo by Bryan Bedder/Getty Images)

Katy Perry and Harry Belafonte attend the Unicef SnowFlake Ball at Cipriani 42nd Street on November 27, 2012 in New York City. (Photo by Bryan Bedder/Getty Images)

Photo: Getty Images

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Katy Perry and Selena Gomez sparkle at UNICEF Snowflake Ball

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Katy Perry and Selena Gomez were among the guests at the UNICEF Snowflake Ball in New York City on Tuesday. The annual black-tie affair celebrates the lighting of the UNICEF Snowflakes and honor those who support the charitable organization.